D-chiro-inositol (cis-1,2,4-trans-3,5,6-cyclohexol) is a stereoisomer of myo-inositol (cis-1,2,3,5-trans-4,6-cyclohexanehexol) in a form that 3-hydroxyl group is epimerized (FIG. 1). D-chiro-inositol, which is a main component of inositol-phosphoglycan (IPG), has been reported as an important medium of insulin signal transduction and also known as being effective in the treatment of type II diabetes. D-chiro-inositol is mainly found in eucaryota and biosynthesized by means of the epimerization of myo-inositol.
D-chiro-inositol is mainly prepared by means of the hydrochloric acid hydrolysis of D-pinitol or kasugamycin (U.S. Pat. No. 5,827,896, U.S. Pat. No. 5,091,596, U.S. Pat. No. 5,463,142 and U.S. Pat. No. 5,714,643). However, as raw materials, D-pinitol or kasugamycin is expensive and organic synthesis (U.S. Pat. No. 5,406,005, WO 96/25381) is also known, but not economically feasible due to difficult separation of by-products.
Yamamoto et al presented a method for converting myo-inositol into chiro-inositol by using germs which express MI epimerase of Agrobacterium sp. AB10121 (JP2001-006878, WO2002/055715). The method of Yamamoto et al is capable of preparing D-chiro-inositol from myo-inositol at an approximately 15% yield.
Throughout the present specification, a number of papers and patent documents are referred to and their citations are indicated. The disclosed contents of cited papers and patent documents are included herein by reference in this entirety, so that the related art and the contents of the present invention could be more clearly described.